卫星广播电视村村通

１我国卫星数字电视的发展我国卫星数字电视起步较早，１９９５年１１月３０日中央电视台通过我国中星５号卫星播出了五套卫星数字电视节目，后于１９９６年６月转到亚洲２号卫星Ｋｕ频段（通信频段）正式播出。中央电视台的卫星数字电视是采用ＭＰＥＧ２－Ｄｉｇｉｃｉｐ...     

“亚卫2号”简介

“亚卫２号”简介聂新元“亚洲卫星２号”是亚洲卫星公司继“亚卫１号”之后的又一颗用于通信和广播的卫星，也是目前亚洲地区最大的通信卫星。“亚卫２号”的轨道位置为东经１００．５°，设计寿命为１５年。较之“亚卫１号”，“亚卫２号”有了很大的改进。它不仅具有Ｃ...     

捕捉鑫诺1号《上海卫视》的简要方法

先把天线对准亚洲２号１００．５°,用模拟接收机调出中央第４套节目。然后用学生使用的量角器和直尺,量出仰角和方位角的距离。如仰角等于２８°如图１,方位等于４８．４ｃｍ（如图２）,再把天线调整到亚洲１号１０５．５°凤凰卫视节目,同样量出仰角和方位角,如仰角等于３０°,方位等于５７．３ｃｍ。（根据亚洲１号和亚洲２号的实测仰角和方位角之差,仰角为２°,方位为８．９ｃｍ）。在亚洲１号的基础上把仰角上调２°,方位向东微调８．９ｃｍ（这就是鑫诺卫星１号１１０．５°在你所处地区的定点位置）,同时换上带信号强度显…     

中数传媒签亚洲卫星新转发器 中央平台频道集成规模再上新台阶

2006年3月17日，中央数字电视传媒有限公司（中数传媒）与亚洲卫星有限公司（亚洲卫星）签署了亚洲四号卫星C波段转发器租用协议。此举为日后中央节目平台集成更多的数字付费频道，更好地服务于付费电视市场提供了有效技术保障。     

俄罗斯RTR-Planeta频道加盟亚洲2号卫星

亚洲卫星公司与Russian State Television and Radio Broadcasting Company（RTER—俄罗斯国家电视及电台广播公司）2月15日宣布．RTR旗下之国际电视频道RTR-Planeta已经开始在亚洲2号卫星上广播．为亚太地区的俄语观众提供新闻、体育、电影及文化信息等电视节目。     

中数传媒签亚洲卫星新转发器

（本刊讯）3月17日，中央数字电视传媒有限公司（中数传媒）与亚洲卫星有限公司（亚洲卫星公司）在北京签署了亚洲4号卫星C波段转发器使用协议。根据协议．中数传媒将增加租用亚洲4号卫星转发器的数量，以进一步扩充中央数字付费电视平台播出的频道数量，更好地服务于极具发展潜力的中国付费电视市场。中数传媒总经理沈向军和亚洲卫星公司中国部总经理陈力群分别代表双方在协议书上签字，并互致高度评价，表示相互支持。不断加强合作．共同推动我国数字付费电视业务的发展。国家广电总局社管司副司长罗建辉、科技司办公室主任杨晓东和计财司产业发展处处长金北宁出席了签字仪式。     

全球卫星音(视)频广播业务近期发展--Worldspace篇

在美国卫星音频广播寡头运营商XM和Sirius生意兴隆的同时，首开全球卫星音频广播业务之先河的世广卫星集团公司（Worldspace，世广）公司近期也获得了较好发展，截至2005年底，全球用户已逾10万。近年来，公司利用其在轨的亚洲之星（AsiaStar）和非洲之星-1（AfriStar 1）将服务重点集中在印度、中国、西欧和中东地区。即将发射的非洲之星-2（AfriStar 2），将使世广在欧洲的服务能力进一步增强。     

卫星电视接收应注意的问题

凡从事过寻星收调卫视节目者都有同感：有的卫视信号很容易接收（如亚洲２号、亚洲３Ｓ和亚太 １Ａ的数、模信号）,而有的星接收起来并不容易（如８８°Ｅ的中新１号Ｋｕ波段）,甚至费了很多时间进行接收,却一无所获,直到寻星失败。这是什么原因呢？只要通过分析卫星所在经度、下行频率、极化波方向、波束、功率和接收点经纬度,就可知其个中原由。 １．卫星电视信号的接收点经纬度与卫星所在经度的关系 （１）卫星定点原理及接收天线方位角、仰角的形成 我国位于北纬,属东半球国家。根据卫星定点（科研、防灾、军事卫星除外）都在地球…     

C波段双星馈源盘的再利用

自从亚洲2号卫星出现故障之后,央视一套及部分省台转至亚洲3S和亚太6号（原亚太1A）卫星上传送.为了更好地接收亚洲3S卫星上的央视和省台等卫视节目,大家纷纷把1.5米中卫锅转动起来,对准亚洲3S卫星.于是,原来用于一锅双星接收亚洲2号和亚洲3S卫星的双星馈源纷纷“下岗待业”,成为了大家手中的鸡肋--食之无味,弃之可惜.阿杰的双星馈源也不例外.     

从亚洲五号上看4K高清FIFA世界杯

近日,亚洲五号卫星为欧洲广播联盟（简称EBU）直播世界杯六十四场高清赛事以及提供4K超高清电视信号传送。4K信号的赛事现场直播分别于6月28日（十六强赛）、7月4日（四强决赛）和7月13日（总决赛）提供。亚洲五号卫星是亚洲最受欢迎的体育内容电视节目传送平台之一,亚洲系列卫星资源为世界上三分之二的人口提供广播及通信服务,现转播450多套电视及广播频道,为超过7．1亿户家庭提供多项电视服务。     

接收“亚卫2号”天线定向等值线图

本文设计绘制了接收“亚卫２号”、“中星５号”的天线方位角，仰角的等值线图。     

Studies of CW lasing action in CO2-CO,N2O-CO, CO2-H2O, and N2O-H2O mixtures pumped by blackbody radiation

A proof of principle experiment to evaluate the efficacy of CO and H₂O in increasing the power output for N₂O and CO ₂ lasing mixtures has been conducted and theoretically analyzed for a blackbody radiation-pumped laser. The results for N₂ O-CO, CO₂-CO, N₂O-H₂O and CO₂-H₂O mixtures are presented. Additions of CO to the N₂O lasant increased power up to 28% for N₂O laser mixtures, whereas additions of CO to the CO₂ lasant, and the addition of H₂O to both the CO₂ and N₂O lasants, resulted in decreased output power     

Fast algorithms for 2-D circular convolutions and number theoretictransforms based on polynomial transforms over finite rings

We develop new fast algorithms for 2-D integer circular convolutions and 2-D number theoretic transforms (NTT). These new algorithms, which offer improved computational complexity, are constructed based on polynomial transforms over Z_p; these transforms are Fourier-like transforms over Z_p, which is the integral domain of polynomial forms over Z_p[x]. Having defined such polynomial transforms over Z_p we prove several necessary and sufficient conditions for their existence. We then apply the existence conditions to recognize two applicable polynomial transforms over Z_p. One is for p equal to Mersenne numbers and the other for Fermat numbers. Based on these two transforms, referred to as Mersenne number polynomial transforms (MNPT) and Fermat number polynomial transforms (FNPT), we develop fast algorithms for 2-D integer circular convolutions, 2-D Mersenne number transforms, and 2-D Fermat number transforms. As compared to the conventional row-column computation of 2-D NTT for 2-D integer circular convolutions and 2-D NTT, the new algorithms give rise to reduced computational complexities by saving more than 25 or 42% in numbers of operations for multiplying 2 ⁱ, i⩾1; these percentages of savings also grow with the size of the 2-D integer circular convolutions or the 2-D NTT     

Yet another result on multi-log2N networks

One-to-many connection (i.e., multicast) is an important communication primitive used in parallel processing and high-speed switching in order to simultaneously send data from an input to more than one output. We prove that for even (respectively, odd) n, a multi-log₂N network is strictly nonblocking for a one-to-many connection traffic if it is designed by vertically stacking at least (δn)/4+1((δ/2)(n-1)+1) planes of a log₂N network together, where N=2ⁿ, δ=2^[n/2], and [x] denotes the greatest integer less than or equal to x. We thus give answer to the open problem and introduce yet another strictly nonblocking multicast network. The characterized network has self-routing capability, regular topology, O(2log₂N+2log₂(log₂N)) stages, and fewer crosspoints than the Clos network for N⩾512. We then extend multi log₂N multicast networks to the fanout restricted nonblocking networks. It turns out that the multi-log₂N network nonblocking in a strict-sense for a one-to-one connection traffic is also wide-sense nonblocking for a multicast traffic in which the fanout of any connection does not exceed δ, provided that for even (respectively, odd) n, the fanout capability of each log₂N network is restricted to stage (n/2)(((n-1)/2)+1) through n-1     

High‐Performance Overall CO2 Splitting on Hierarchical Structured Cobalt Disulfide with Partially Removed Sulfur Edges

The ability to develop bifunctional electrocatalysts for concurrent CO₂ reduction reaction (CO₂RR) and oxygen evolution reaction (OER) is the key to the practical application of CO₂ splitting to produce CO. However, this remains a grand challenge. Herein, a robust strategy to rationally craft hierarchical structured bifunctional electrocatalysts composed of 3D CoS₂ nanocages interconnected on 2D CoS₂ nanosheet arrays (denoted hierarchical CoS₂ nanocages) for high‐performance CO₂ splitting is developed. The subsequent calcination removes the partial S edges of CoS₂, thereby strongly suppressing the hydrogen evolution reaction (HER) of CoS₂. By combining theoretic and experimental results, for the first time, it is discovered that the plane S of CoS₂, instead of S edges, are highly active for CO₂RR but inactive for HER, rendering the plane S as ideal active sites for CO₂RR. Intriguingly, the composition tuning via calcination and the presence of a hierarchical architecture confer hierarchical CoS₂ nanocages respective outstanding CO₂RR and OER performance. Notably, the hierarchical CoS₂ nanocages can be exploited as bifunctional electrocatalysts for overall CO₂ splitting to yield the current density of 1 mA cm^?2 at a small cell voltage of 1.92 V, much lower than the widely reported values (>2.5 V).     

Generalized Kasami Sequences: The Large Set

In this correspondence, new binary sequence families F^k of period 2ⁿ-1 are constructed for even n and any k with gcd(k,n)=2 if n/2 is odd or gcd(k,n)=1 if n/2 is even. The distribution of their correlation values is completely determined. These families have maximum correlation 2^n/2+1 and family size 2^3n/2 + 2^n/2 for odd n/2 or 2^3n/2+2^n/2-1 for even n/2. The proposed families include the large set of Kasami sequences, where the k is taken as k=n/2+1.     

A Multi-Mode Sigma-Delta ADC for GSM/WCDMA/WLAN Applications

The demand for new telecommunication services requiring higher capacities, data rates and different operating modes have motivated the development of new generation multi-standard wireless transceivers. In multi-standard design, sigma-delta based ADC is one of the most popular choices. To this end, in this paper we present cascaded 2-2-2 reconfigurable sigma-delta modulator that can handle GSM, WCDMA and WLAN standards. The modulator makes use of a low-distortion swing suppression topology which is highly suitable for wide band applications. In GSM mode, only the first stage (2nd order ∑-Δ ADC) is used to achieve a peak SNDR of 88dB with over-sampling ratio of 160 for a bandwidth of 200KHz and for WCDMA mode a 2-2 cascaded structure (4th order) is turned on with 1-bit in the first stage and 2-bit in the second stage to achieve 74 dB peak SNDR with over-sampling ratio of 16 for a bandwidth of 2MHz. Finally, a 2-2-2 cascaded MASH architecture with 4-bit in the last stage is proposed to achieve a peak SNDR of 58dB for WLAN for a bandwidth of 20MHz. The novelty lies in the fact that unused blocks of second and third stages can be made inactive to achieve low power consumption. The modulator is designed in TSMC 0.18um CMOS technology and operates at 1.8 supply voltage.     

A novel delineation mechanism for the ATM adaptation layer 2 over wireless ATM networks

The ATM adaptation layer 2 (AAL2) has been standardized by the ITU‐T for the support of low data rate and delay‐sensitive applications, such as voice, over ATM networks. One of the main characteristics of the AAL2 standard is the support for multiplexing information at the expense of introducing a new frame structure inside the payload of the ATM cells. The AAL2 standard introduces a mechanism for the delineation of the AAL2 packets and it has been found that the delineation mechanism reduces the performance of AAL2 in the presence of channels with high bit error rates. In this paper, a novel delineation mechanism is proposed for AAL2 to be used over highly error‐prone channels, such as wireless links. The proposed mechanism improves the performance (i.e. reduces packet loss) of the AAL2 standard in the presence of bit errors and in some cases reduces the overhead required for the delineation of the AAL2 packets. Copyright © 2002 John Wiley & Sons, Ltd.     

GaAs、GaP、InP、InGaAsP、AlGaAs、InAlGaAs的化学腐蚀研究

为研制全集成光开关、微片式激光器等，对ＧａＡｓ、ＧａＰ、ＩｎＧａＡｓＰ、ＩｎＡＩＧａＡｓ、ＡｌＧａＡｓ等材料的化学腐蚀进行了实验研究。为了研制ＩｎＡｌＧａＡｓ／ＩｎＡｌＡｓ／ＩｎＡｌＧａＡｓ微片式激光器，开发了Ｈ３ＰＯ４／Ｈ２Ｏ２／Ｈ２Ｏ薄层腐蚀液和ＨＣｌ／Ｈ２Ｏ选择性腐蚀液；为了研制ＩｎＧａＡｓＰ／ＩｎＰ／ＩｎＧａＡｓＰＴｂａｒ型光波导，开发了ＨＣｌ／Ｈ３ＰＯ４／Ｈ２Ｏ２薄层腐蚀液和ＨＣｌ／Ｈ２Ｏ２选择性腐蚀液；为了研制ＧａＰ、ＩｎＧａＰ光波导，开发了ＨＣｌ／ＨＮＯ３／Ｈ２Ｏ薄层腐蚀液。它们都具有稳定、重复性好、速率可控、腐蚀后表面形貌好等特点。除此之外，蚀刻成的ＧａＰ光波导侧壁平滑无波纹起伏。此种结果尚未见报导。     

Heterologous expression of G protein-coupled receptors in U-2 OS osteosarcoma cells

Recombinant baculoviruses, in which the insect cell-specific polyhedrin promoter has been replaced with a mammalian cell-active expression cassette (BacMam viruses), are efficient gene delivery vehicles for many mammalian cell types. BacMam viruses have been generated for expression of G protein-coupled receptors (GPCRs) and used to establish Ca2+mobilization assays in HEK-293 human embryonic kidney cells and U-2 OS human osteosarcoma cells. U-2 OS cells are highly susceptible to BacMam-based gene delivery and lack many of the endogenous receptors present on HEK-293 and other mammalian cell lines typically used for heterologous expression of GPCRs. U-2 OS cells were found to have a null background for muscarine, ADP, ATP, UTP, UDP, and lysophosphatidic acid (LPA). Consequently, U-2 OS cells transduced with BacMam constructs encoding the muscarinic acetylcholine receptors (M1, M2, M3, M4, and M5subtypes), the P2Y receptors (P2Y1, P2Y2), or the LPA receptors (EDG-2, EDG-7) were used for the establishment of whole-cell Ca2+mobilization assays, assays that cannot readily be established in HEK-293 cells. U-2 OS cells were susceptible to simultaneous expression of multiple genes delivered by BacMam vectors. In U-2 OS cells the functional expression of the Gi-coupled M2and M4receptors was dependent on co-expression of the receptor and a G protein chimera, both of which were delivered to the cells via BacMam viruses. The use of U-2 OS cells and BacMam-based gene delivery has facilitated development of whole-cell-based GPCR functional assays, especially for P2Y, muscarininc acetylcholine, and LPA receptors.